1. Field of the Invention
This invention relates to a composition which is useful for displacing liquid water from the surfaces of articles.
2. Description of the Prior Art
In many machining and cleaning operations, metal parts are brought into contact with water, with the result that the finished metal surface remains wet. As is well known, water leads to more rapid corrosion of these metal surfaces. Many machined metal parts, such as bearings and precision valve components, cannot tolerate corrosion because of the fine tolerances usually required. In addition, certain metal parts, and particularly precision metal parts, must be completely dry before they are assembled. Ball, needle and roller bearings, for example, if inserted in a race while wet will corrode and freeze the bearing assembly. Accordingly, it is necessary that many metal parts be completely dried immediately after the machining or cleaning operation, and before they are assembled. A similar need exists for drying plastic and glass surfaces, particularly when these parts are to be used in combination with metal parts.
Heretofore, such parts have been dried by simple heating, but this is often undesirable since heating in the presence of water may cause corrosion. Moreover, heating requires handling which is also undesirable. Water has also been removed by treating with certain solvents such as acetone or alcohol. However, such liquids are toxic and flammable, and thus present operational hazards. Accordingly, a need exists for a method of removing water from surfaces without heating in the presence of water or using flammable or toxic solvents.
As is well known, ferrous metal surfaces will rust, particularly if the surface is free of protective materials. Degreased metals are particularly prone to rusting since the surface is completely free of materials which would otherwise prevent contact of the surface with oxygen.
Rusting of many surfaces, while undesirable, is not particularly serious, providing the rust is removed before further treating such as painting, plating or the like. However, the slightest amount of rusting of the surface of precision ferrous metal parts, for example, ball bearings and the like, is a serious matter since such parts are machined and finished to very fine tolerances. Many methods have been developed for treating ferrous metal surfaces to prevent rusting. Because none of these methods is 100% effective in all cases, there is a continuing need for improved methods of rust prevention.
The removal of liquid water from the surfaces of articles by means of organic water-immiscible liquids is well known. As evidence of the state of the art is U.S. Pat. No. 3,903,012 wherein is disclosed a liquid-water displacement composition comprised of a surfactant dissolved in a fluorine-containing compound having a solubility parameter of less than about 8, a density of at least about 1.3 grams/cubic centimeter at room temperature and a boiling point above about 20.degree. C., said composition having an interfacial tension with water of up to about 6 dynes/centimeter and a water-solubilizing capability of less than about 750 parts/million. Additional evidence as to the state of the art in the field of liquid-water displacement compositions may be found in the background section of the above patent.
Although water displacement compositions comprising a surfactant and a normally liquid organic solvent are well known, their usefulness may be impaired by a tendency of such a composition to form an emulsion when admixed with water. This characteristic is particularly detrimental to the composition if the emulsion is difficultly or only very slowly separable into two phases. It is suggested in the aforesaid U.S. Pat. No. 3,903,012 that a small amount of a C.sub.1-6 mono-alcohol may be added either to prevent the formation of such an emulsion or to hasten separation of the two phases.
Other examples of prior art in the field of liquid-water displacement compositions, processes and apparatus include U.S. Pat. No. 3,386,181 and U.S. Pat. No. 3,397,150. In the former are disclosed a process and apparatus for removing water from the surfaces of non-absorbent articles. In carrying out the process the articles are immersed in a bath having both a turbulent region and a quiescent region, the bath containing as its principal component a water-immiscible solvent which has a boiling point of about 20.degree.-60.degree. C. and a density of at least about 1.1 at 20.degree. C. and does not form an azeotrope containing more than about 4% of water or boiling more than 8.degree. C. below the boiling point of the water-immiscible solvent. In U.S. Pat. No. 3,397,150 is disclosed a process for removing water from solid surfaces by treating the surfaces with a composition containing trichlorotrifluoroethane and a solute derived from a mono- or di-(C.sub.6-20 alkyl) phosphate ester and a saturated aliphatic amine having 1-3 alkyl groups attached to the nitrogen atom and a total of 6-20 carbon atoms, for example, 2-ethylhexylammonium octyl phosphate.